Influence of Aggregate Size and Microrelief on Development of Surface Soil Crusts

Abstract

AbstractThe rate of water entry during rainfall has implications for crop agronomy, erosion, and groundwater recharge. This study investigated the influences of aggregate size, microrelief and rainfall intensity on development of surface crusts and infiltration. Infiltration rate and hydraulic resistance of developing crusts on two soils under various surface conditions and simulated rainfall were measured. The two soils were Webster clay loam (fine loamy, mixed mesic Typic Haplaquoll) and Port Byron silt loam (fine‐silty, mixed, mesic Typic Hapludoll). Aggregates with sizes of <1, <2, 1 to 2, 2 to 5, 5 to 19, 19 to 25, and 25 to 50 mm were studied. Final or steady‐state infiltration rates were similar for all aggregate sizes of both soil types, but development of a soil crust was delayed when the surface was made up of aggregates >19 mm in diameter. Large aggregates (clods) were a source of finer materials for the development of soil crusts. Microrelief effects were simulated by creating a ridge‐furrow configuration in a box. Ridge‐furrow microrelief did not influence total infiltration and was only effective in modifying the spatial distribution of water in the soil during the early phase of crust development. Infiltration rates, when measured using different rainfall intensities, could be described by a single curve when expressed as a function of cumulative rainfall rather than time. Total rainfall or rainfall energy may be better parameters for describing soil crust development than rainfall intensity.